Liver failure is associated with significant morbidity and a mortality rate exceeding 40,000 patients annually in the United States. Liver transplantation is the treatment of choice for patients with liver failure. Liver transplantation, however, has several shortcomings, including a scarcity of donor organs, the need for lifelong immunosuppression following transplantation, and the inability to predict or control organ donation. Although living donation addresses some of these problems, less than 20% of patients waiting for a liver transplant are expected to benefit from such a treatment. In addition, many patients with liver failure are not suitable candidates for transplantation due to age, compromised health, or other contraindications. Further, the problem of finding suitable donor livers is expected to increase as a result of the hepatitis C epidemic affecting over 2 million U.S. citizens. Hepatitis C leads to end-stage liver disease in 5-20% of the known cases. Liver support devices have been used to help sustain patients until an organ is available for liver transplantation. The efficiency of such devices, however, has been limited by a number of environmental and nutrient limitations within the device. Therefore, there is a need for an efficient and effective artificial liver.